This invention relates to a vane compressor for compressing a fluid such as refrigerant circulating within an air conditioning system.
A vane compressor in general comprises a drive shaft arranged to be rotated by a prime mover; a rotor arranged for rotation in unison with the drive shaft and formed with a plurality of axial slits in its outer peripheral surface; a plurality of vanes radially movably received in the axial slits; a pump housing having an endless camming inner peripheral surface and accommodating the rotor and the vanes, the rotor, vanes and pump housing defining in cooperation pump working chambers therebetween; and a casing enclosing the pump housing to define a discharge pressure chamber between itself and the pump housing. Rotation of the rotor causes gaseous medium such as refrigerant to be pressurized within the pump working chambers and discharged to the outside through the discharge pressure chamber.
In compressors of this kind are generally employed mainly two types of rotor supporting means. One of them is used in vane compressors manufactured by the assignee of the present application, according to which, as known e.g. from U.S. Pat. No. 4,244,680, the drive shaft has its end portion fitted through the rotor in a manner radially supporting it, with its end face located on substantially the same plane with an associated end face of the rotor. The drive shaft radially supportedly penetrates through a radial bearing portion formed in one of two opposite side blocks forming the two end walls of the pump housing. The other type rotor supporting means, which is known e.g. from U.S. Pat. No. 3,250,460, is such that the drive shaft extends through the rotor, with its end projecting from an associated end face of the rotor and supportedly fitted in a corresponding side block of the pump housing, while simultaneously the rotor is also radially supported by the drive shaft along its entire length.
According to the above two conventional rotor supporting means, the drive shaft is fitted through the rotor along the entire length of the latter. That is, a considerable portion of the drive shaft is present within the rotor so that the substantial mass of the rotor portion is large, resulting in large energy loss during rotation of the rotor.